Interference eliminator for radioreceivers



March 24, 1931. M, W|EH| INTERFERENCE ELIMINATOR FOR RADIORECEIVERS Filed July 2. 1929 INVENTOR. M 74 mi 31 BY Och "3 ATTORNEY Patented Mar. 24,1931

claims.

frs-nrf for-ri c' ANDREW M. WIEHL, or SAN FRANCISCO, Crimean... rssmaoa on ons-narrate HARRY n. BAUMANN, or oA LANncALrroan-rr, 1

rn'rnnrnnnnon ntnvrrnaron r03 nanronnonlvnns Application filed July 2, 1929. Serial No. 375,492.

The invention is for a radio interference eliminator. It is found exceedingly difficult to obtain satisfactory reception over a radio in many localities due to the presence in proximity to the receiving point of high tension electric wires, such for instance, as trolley wires, electric power feeder wires and the like, due to the radiating from such wires of an electric current.

- It is one of the objects of the invention to provide an interference eliminator for radios that will be particularly efiective in eliminating radio interference resulting from alternating current waves from high tension electric power lines and the like.

The invention will be hereinafter fully set forth and particularly pointed out in the In the accompanying drawings; Figure 1 is a perspective view showing the interference eliminator unit mounted in a suitable casing. I

Flgure 2 1s a wiring diagram showing the manner of electrically connecting the various elements comprising the eliminator.

Figure 3 is a wiring diagram indicating the manner in which the eliminator is emments within the casing.

ployed with a radio receiving set.

- For a clearer and more comprehensive understanding of the device reference may now be had a the drawing. ganization the invention contemplates a radio frequency amplifier designated by the reference character 10 and is associated with a connector 11 connected thereto'by cable 17. The amplifier 1.0 is of the usual type of construction having a grid 12, plate 13, and filament 14: which is provided with negative and positive terminals 15 and 16 respectively. In the interest of economy the connector 11 may be formed from a used radio tube base having a plate contact pin 18, a'grid contact pin 19, a negative filament contact pin 20and a positive contact pin 21, the circuit wires in the cable 17 for convenience ofintroduction' into the casing 39 where the wires are separated for connection with the various ele- Wire 22 connects the plate 13 with contact pin 18. WVire 23 In its general or-' connects the grid 12 with the grid contact pin 19. l/Vire 24 connects the negative filament terminal 15 with the negative filament contact pin 20. Wire 25 connects the posi--' tive filament terminal 16with the positive filament contact pin 21. lVire 26 connects the positive filament wire 25 with antenna terminal 33 of a radio receiving set;

In order to hook up the device to a radio set the first radio frequency amplifier is withdrawn from its socket and the connecter 11 is inserted therein, when the wire 26 may be connected to the antenna terminal 33 of the radio receivingset and the wires 30 and 31 connected to the outside aerial .32. Wire 30 connects the grid 12 to the antenna 32. A variable condenser 29 is connected between the antenna 32 andthe plate 13.by the wire 31. It will be understood that the term antenna is used in its broadest sense. i

In Figure 3, the grid terminal G, the plate terminal P and the filamentterminal F, of the socket usually occupied by the electron tube in'the first step of the radio frequency amplifying'portion of a radio receiving set, are indicated as connected to corresponding terminals of the electron tube-10 when the connectorll is in place in the receiving set. I

It .will be understood that the wiring diagram of the circuit elements of the radio receiving set is conventional.

'A rheostat 27 is connected by wire 26 in 3 series connection between the filament 14 and the antenna terminal 33 of the radio-receiving set, and is adjustable to eliminate noise in the receiving set caused bythe high tension power lines. A rheostat 28 is connected by;

wire 22 between the plate 13 and the plate terminal P, and is adjustable'to control the volume oftheoutput of the receiving set, and

to controloscillations inthe circuits imme-- an electron tube having a plate, a grid, and

a filament, a condenser connected in parallel with the said plate and the said grid, antenna means connected to the said grid, conductor means connecting the said p at g id and filament respectively to the plate, grid and filament terminals of the tube socket of the radio frequency amplifying stage of the receiving set and from which socket an electron tube has been removed, and a rheostat connected between the filament of the first named electron tube and the'antenna terminal of the receiving set. I

In testimony whereof I have afiixed my signature. v V Y ANDREW M. 

